Apparatus and method for forming an optical fiber device

ABSTRACT

An apparatus for forming an optical fiber device comprising at least one optical fiber includes a mold having a forming surface, means for heating the mold or the optical fiber, and an insert defining at least one optical fiber locator passage for guiding at least one optical fiber toward the forming surface. A method for forming an optical fiber device from at least one optical fiber includes the steps of heating the optical fiber or a forming surface of a mold to a temperature greater than a melting temperature of the optical fiber; advancing the optical fiber into contact with the forming surface of the mold such that a portion of the optical fiber is formed into a shape inversely corresponding to a shape of the forming surface; and withdrawing the optical fiber from the forming surface.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a Divisional of U.S. patent application Ser. No.11/775,003, filed Jul. 9, 2007, which claims priority to United KingdomApplication Serial No.: 0613721.0, filed Jul. 10, 2006, both of whichare incorporated herein by reference in their entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to forming optical fiber devices.

2. Description of Related Art

Optical fiber devices, such as optical fiber cables, are widely used incommercial and personal equipment. In many implementations, the ends ofsuch optical fiber devices exhibit specified configurations.Conventionally, the ends of many such optical fiber devices are groundand polished to achieve the desired configurations. Generally, grindingand polishing operations are time consuming and costly. Because eachoptical fiber device is processed individually, inconsistencies betweenoptical fiber devices naturally arise. These problems are exacerbatedwhen the optical fibers of such devices being processed are small and inimplementations wherein the geometric and/or dimensional characteristicsof the fiber optic device end require tight tolerances.

Some optical fiber devices require that ends of two or more opticalfibers be optically coupled or joined. Traditionally, the optical fibersare joined using optical resins or the like that are applied to theoptical fibers. Conventional optical resins, however, are not compatiblewith some environments, such as high temperature environments. Theoptical resins may soften, deteriorate, or otherwise fail to operateproperly in such environments. Moreover, the resin joining the opticalfibers must be ground and polished to achieve a desired endconfiguration in some implementations. The grinding and polishing ofresin portions that join optical fibers suffer from the same problemsdiscussed above concerning the grinding and polishing of optical fibers.

There are many ways to form optical fiber devices that are well known inthe art. However, considerable shortcomings remain.

BRIEF SUMMARY OF THE INVENTION

There is a need for an improved apparatus and method for forming opticalfiber devices.

Therefore, the present invention provides an improved apparatus andmethod for forming an optical fiber device.

The apparatus includes a mold having a forming surface, means forheating the mold or the optical fiber or fibers comprising the opticalfiber device, and an insert defining at least one optical fiber locatorpassage for guiding at least one optical fiber toward the formingsurface.

An alternative apparatus for forming an optical fiber device is alsoprovided. This apparatus includes a mold having a forming surface andmeans for heating the mold or the optical fiber or fibers comprising theoptical fiber device. The apparatus further includes an insert definingat least one optical fiber locator passage for guiding at least oneoptical fiber toward the forming surface and a guide affixed to themold, the guide defining a recess configured to receive the insert andan optical fiber locator passage leading from the at least one opticalfiber locator passage of the insert toward the forming surface.

In another aspect, the present invention provides a method for formingan optical fiber device from at least one optical fiber. The methodincludes the steps of heating a forming surface of a mold to atemperature greater than a melting temperature of the at least oneoptical fiber; advancing the at least one optical fiber into contactwith the forming surface of the mold such that a portion of the at leastone optical fiber is formed into a shape inversely corresponding to ashape of the forming surface; and withdrawing the at least one opticalfiber from the forming surface. Alternatively, heat may be applieddirectly to the optical fiber to melt it to acquire the mold shape.

The present invention provides significant advantages, including: (1)joining a plurality of optical fibers without the use of resins or thelike; (2) providing a means for joining optical fibers into opticalfiber devices that are capable of withstanding harsh environments, suchas high temperature environments; and (3) forming ends on optical fiberdevices without grinding and/or polishing the ends.

Additional features and advantages will be apparent in the followingwritten description.

BRIEF DESCRIPTION OF THE DRAWINGS

The novel features characteristic of the invention are set forth in theappended claims. However, the invention itself, as well as a preferredmode of use and further advantages thereof, will best be understood byreference to the following detailed description when read in conjunctionwith the accompanying drawings, in which the leftmost significantdigit(s) in the reference numerals denote(s) the first figure in whichthe respective reference numerals appear, wherein:

FIG. 1 is a top, plan view of a plurality of optical fibers prior toprocessing by the present invention;

FIG. 2 is a top plan view of the plurality of optical fibers of FIG. 1after processing by the present invention to join the optical fibersand, thus, form an optical fiber device having a desired endconfiguration;

FIG. 3 is a top, plan view of a first illustrative embodiment of anapparatus according to the present invention for forming an opticalfiber device;

FIG. 4 is a side, elevational view of the apparatus of FIG. 3;

FIG. 5 is an end, elevational view of the apparatus of FIG. 3;

FIGS. 6-9 are cross-sectional views of the apparatus of FIG. 3, takenalong the line 6-6 in FIG. 4, depicting one particular method accordingto the present invention of forming an optical fiber device;

FIG. 10 is a top, plan view of a second illustrative embodiment of anapparatus according to the present invention for forming an opticalfiber device;

FIG. 11 is a side, elevational view of the apparatus of FIG. 10;

FIG. 12 is an end, elevational view of an insert of the apparatus ofFIG. 10;

FIG. 13 is an end, elevational view of a forming assembly of theapparatus of FIG. 10;

FIGS. 14-17 are cross-sectional views of the apparatus of FIG. 10, takenalong the line 14-14 of FIG. 11, illustrating a method according to thepresent invention for forming an optical fiber device;

FIG. 18 is a top, plan view of a third illustrative embodiment of anapparatus according to the present invention for forming an opticalfiber device; and

FIG. 19 is a top, plan view of a fourth illustrative embodiment of anapparatus according to the present invention for forming an opticalfiber device.

While the invention is susceptible to various modifications andalternative forms, specific embodiments thereof have been shown by wayof example in the drawings and are herein described in detail. It shouldbe understood, however, that the description herein of specificembodiments is not intended to limit the invention to the particularforms disclosed, but on the contrary, the intention is to cover allmodifications, equivalents, and alternatives falling within the scope ofthe invention as defined by the appended claims.

DETAILED DESCRIPTION OF THE INVENTION

Illustrative embodiments of the invention are described below. In theinterest of clarity, not all features of an actual implementation aredescribed in this specification. It will of course be appreciated thatin the development of any such actual embodiment, numerousimplementation-specific decisions must be made to achieve thedeveloper's specific goals, such as compliance with system-related andbusiness-related constraints, which will vary from one implementation toanother. Moreover, it will be appreciated that such a development effortmight be complex and time-consuming but would nevertheless be a routineundertaking for those of ordinary skill in the art having the benefit ofthis disclosure.

Referring to FIGS. 1 and 2, the present invention represents a methodand apparatus for thermally fusing ends 101 and 103 of a plurality ofoptical fibers 105 and 107, respectively, to form an optical fiberdevice 201. During the fusing process, an end 203 of optical fiberdevice 201, which comprises fused ends 101 and 103 of optical fibers 105and 107, respectively, is thermally formed into a desired configuration.In the illustrated embodiment, end 203 exhibits a configuration thatprovides for a light ray 205 propagating through first optical fiber 105toward end 203 to be reflected by end 203, such that light ray 205propagates through second optical fiber 107 away from end 203.Similarly, a light ray 207 propagating through second optical fiber 107toward end 203 is reflected by end 203, such that light ray 207propagates through first optical fiber 105 away from end 203. In theillustrated embodiment, end 203 includes a ridge 209 that is tangent tofibers 105 and 107. End 203, in the illustrated embodiment, exhibits aright angle with ridge 209 disposed at a vertex of the right angle. Thepresent invention is particularly useful in the manufacture of cable andsystem embodiments disclosed in UK Patent GB 2 404 017 B, entitled“System for deploying double-ended distributed temperature sensingsystems”, which is incorporated herein by reference.

FIGS. 3-5 depict a first illustrative embodiment of an apparatus 301according to the present invention for forming an optical fiber device,such as optical fiber device 201 of FIG. 2, from optical fibers, such asoptical fibers 105 and 107 of FIG. 1. FIG. 3 provides a top, plan viewof apparatus 301; FIG. 4 illustrates a side elevational view ofapparatus 301; and FIG. 5 depicts an end, elevational view of apparatus301 from an insert 303 end. In the illustrated embodiment, apparatus 301comprises a mold 305 operatively associated with a heating means 307.Apparatus 301 further comprises insert 303 that mates with mold 305.Insert 303 defines an optical fiber locator passage 309 that is used toguide the optical fibers as the optical fiber device is formed by mold305, as will be discussed in greater detail below. In the illustratedembodiment, insert 303 defines a rounded, oblong optical fiber locatorpassage 309 that is sized to accommodate two, side-by-side opticalfibers, although other configurations are possible and are encompassedwithin the scope of the present invention, as will also be discussed ingreater detail below.

Referring in particular to FIG. 3, mold 305 defines a forming surface311 having a geometric configuration that inversely corresponds to thedesired end configuration of the optical fiber device to be formed. Inother words, if the desired end configuration of the optical fiberdevice protrudes from the remainder of the optical fiber device, such asin optical fiber device 201 of FIG. 2, forming surface 311 is recessedto form the protruding end of the optical fiber device. In theillustrated embodiment, forming surface 311 defines a right-angle recessfor producing optical fiber device 201. Forming surface 311 exhibits asurface finish that is sufficient to form the end configuration of theoptical fiber device with a desired surface finish. In other words, thesurface finish of forming surface 311 is sufficient to produce a surfacefinish of the optical fiber device end that is within desiredtolerances. It is possible, however, to use an inferior surface finishon the forming surface 311 and post-process the surface of the opticalfiber device 201 to achieve the required surface finish. Thispost-processing may be done by abrasive or flame polishing.

In the illustrated embodiment, mold 305 comprises a plurality ofportions or parts 313 and 315 that are mechanically fastened together.The use of a plurality of portions or parts may facilitate the making ofthe mold 305 to achieve the required tolerances. The scope of thepresent invention, however, is not so limited. Rather, mold 305 maycomprise only a single part or portion. Moreover, even though mold 305is illustrated in FIGS. 3-5 as comprising two portions or parts (i.e.,parts 313 and 315) mechanically fastened together, mold 305 may, inalternative embodiments, comprise more than two portions or partsmechanically fastened together. Furthermore, the plurality of portionsor parts (e.g., parts 313 and 315 of mold 305) may be joined together bymeans other than mechanical fasteners. For example, the plurality ofparts may be joined together by welds. Other means for joining theplurality of portions or parts exist and are encompassed with the scopeof the present invention.

Still referring in particular to FIG. 3, insert 303 includes a face 317adapted to mate with forming surface 311 of mold 305. Preferably, thegeometric configuration of face 317 inversely corresponds to thegeometric configuration of forming surface 311. For example, in theillustrated embodiment, forming surface 311 of mold 305 is recessed,while face 317 of insert 303 protrudes from the remainder of insert 303to mate with forming surface 311.

Referring now to FIGS. 3 and 4, the scope of the present inventionencompasses any heating means 307 suitable for providing thermal energyto mold 305. For example, in one embodiment, heating means 307 comprisesan electromagnetic heating source. Alternatively, heating means 307 maybe used to apply heat directly to that part of the optical fiber orfibers to be melted or fused. This may be done by means of electricalcurrent discharge, for example.

Mold 305 and insert 303 preferably each comprise a material exhibiting amelting point that is higher than a melting point of the optical fibers(e.g., optical fibers 105 and 107 of FIG. 1) to be formed into theoptical fiber device (e.g., optical fiber device 201 of FIG. 2). In oneembodiment wherein optical fibers comprising silica are to be formedinto an optical fiber device, mold 305 and insert 303 comprise titaniumor an alloy comprising titanium as the alloy's principal element.

FIGS. 6-9 depict cross-sectional views of apparatus 301, taken along theline 6-6 in FIG. 4, in which one particular embodiment of a method offorming an optical fiber device (e.g., optical fiber device 201 of FIG.2) is illustrated. Optical fibers 105 and 107, also depicted incross-section, are disposed in optical fiber locator passage 309.

Referring now to FIG. 6, heating means 307 provides thermal energy tomold 305, such that the temperature of mold 305 is equal to or greaterthan the melting temperature of optical fibers 105 and 107. Opticalfibers 105, 107 are placed in optical fiber locator passage 309 andinsert 303 is mated with mold 305. It should be noted that opticalfibers 105, 107 may be placed in optical fiber locator passage 309 priorto mating insert 303 with mold 305.

Referring now to FIG. 7, optical fibers 105 and 107 are advanced (asindicated by arrow 701) through optical fiber locator passage 309 untilcontact is made between forming surface 311 of mold 305 and opticalfibers 105 and 107. Optical fibers 105 and 107 are further urged (asindicated by arrow 701) toward mold 305. As heat is conducted into ends101 and 103 of optical fibers 105 and 107, respectively, portions ofends 101 and 103 melt.

As illustrated in FIG. 8, the melted portions of ends 101 and 103 flowtogether, conforming to the geometric configuration of forming surface311 of mold 305 and fusing optical fibers 105 and 107 together, formingoptical fiber device 201. In a preferred embodiment, forming surface 311of mold 305 is allowed to cool to below the melting point of opticalfibers 105 and 107. Then, as depicted in FIG. 9, insert 303 is withdrawnfrom mold 305 and optical fiber device 201 is removed from insert 303.It should be noted that the scope of the present invention, however,encompasses a method wherein insert 303 is withdrawn from mold 305without first cooling forming surface 311 of mold 305.

It should also be noted that the particular geometric configuration offorming surface 311 of mold 305 and the resulting geometricconfiguration of end 203 of optical fiber device 201 are merelyexemplary. Other configurations exist and such configurations areencompassed within the scope of the present invention.

FIGS. 10-13 depict a second illustrative embodiment of an apparatus 1001according to the present invention for forming an optical fiber device,such as optical fiber device 201 of FIG. 2, from optical fibers, such asoptical fibers 105 and 107 of FIG. 1. FIG. 10 provides a top, plan viewof apparatus 1001 and FIG. 11 provides a side, elevational view ofapparatus 1001. FIG. 12 is an end, elevational view of an insert 1003 ofapparatus 1001. FIG. 13 is an end, elevational view of a guide 1005 anda mold 1007 of apparatus 1001. As in the embodiment of FIGS. 3-5, aheating means 1009 is operably associated with mold 1007 to providethermal energy to mold 1007. Insert 1003 is used to guide a plurality ofoptical fibers (e.g., optical fibers 105 and 107 of FIG. 1) as they arethermally fused by heated mold 1007 to form an optical fiber device(e.g., optical fiber device 201 of FIG. 2) having a desired endconfiguration. In this embodiment, however, insert 1003 mates with guide1005, which has a fixed spatial relationship with respect to mold 1007.

Referring now in particular to FIG. 10, guide 1005 is attached orotherwise affixed to mold 1007. Guide 1005 defines a recess 1011 thatreceives insert 1003, such that insert 1003 mates with guide 1005. Mold1007 includes a forming surface 1013 having a geometric configurationthat inversely corresponds to the desired end configuration of theoptical fiber device to be formed, as discussed above in relation toforming surface 311 (shown in FIG. 3). In the illustrated embodiment,forming surface 1013 defines a right-angle recess for producing opticalfiber device 201. Forming surface 1013 exhibits a surface finish that issufficient to form the end configuration of the optical fiber devicewith a desired surface finish.

In the illustrated embodiment, mold 1007 comprises a plurality ofportions or parts 1015 and 1017 that are mechanically fastened together.As discussed above in relation to mold 305 of FIG. 3, mold 1007 maycomprise only a single part or portion or may comprise any suitablenumber of portions or parts. Moreover, parts 1015 and 1017 may be joinedtogether by means other than mechanical fasteners, such as by welds.Furthermore, while FIGS. 10, 11, and 13 illustrate guide 1005 beingmechanically attached to mold 1007, the scope of the present inventionencompasses embodiments wherein guide 1005 is integral with mold 1007 oris attached to mold 1007 by other means, such as by welds.

As best illustrated in FIG. 12, insert 1003 defines a plurality ofoptical fiber locator passages 1019 and 1021, corresponding to theplurality of optical fibers (e.g., optical fibers 105 and 107 of FIG. 1)being joined into the optical fiber device (e.g., optical fiber device201 of FIG. 2). As will be discussed in greater detail below, opticalfibers are disposed in optical fiber locator passages 1019 and 1021,along which the optical fibers are guided as the optical fiber device isformed by mold 1007. Alternatively, insert 1003 defines a single opticalfiber locator passage, such as optical fiber locator passage 309 of FIG.3. It should be noted that, in the embodiment of FIGS. 3-5, insert 303may alternatively define a plurality of optical fiber locator passages(e.g., optical fiber locator passages 1019 and 1021, corresponding tothe plurality of optical fibers being formed into an optical fiberdevice.

Referring now to FIG. 13, guide 1005 defines an optical fiber locatorpassage 1023 leading to forming surface 1013 of mold 1007. Once insert1003 is mated with guide 1005, optical fibers are advanced throughoptical fiber locator passages 1019 and 1021 of insert 1003 and throughoptical fiber locator passage 1023 of guide 1005 to forming surface 1013of mold 1007, as will be discussed in greater detail below.

Insert 1003, guide 1005, and mold 1007 preferably each comprise amaterial exhibiting a melting point that is higher than a melting pointof the optical fibers (e.g., optical fibers 105 and 107 of FIG. 1) to beformed into the optical fiber device (e.g., optical fiber device 201 ofFIG. 2). In one embodiment wherein optical fibers comprising silica areto be formed into an optical fiber device, insert 1003, guide 1005, andmold 1007 each comprise titanium or an alloy comprising titanium as thealloy's principal element.

FIGS. 14-17 depict cross-sectional views of apparatus 1001, taken alongthe line 14-14 in FIG. 1, in which one particular embodiment of a methodof forming an optical fiber device (e.g., optical fiber device 201 ofFIG. 2) is illustrated. Optical fibers 105 and 107, also depicted incross-section, are disposed in optical fiber locator passages 1019 and1021.

Referring now to FIG. 14, heating means 1009 provides thermal energy tomold 1007, such that mold 1007 is heated to a temperature equal to orgreater than the melting temperature of optical fibers 105 and 107.Optical fibers 105, 107 are placed in optical fiber locator passages1019 and 1021 and insert 1003 is mated with guide 1005. It should benoted that insert 1003 may be mated with guide 1005 prior to placingoptical fibers 105, 107 in optical fiber locator passages 1019, 1021,respectively.

Referring now to FIG. 15, optical fibers 105 and 107 are advanced (asindicated by arrow 1501) through optical fiber locator passages 1019 and1021 until contact is made between forming surface 1013 of mold 1007 andoptical fibers 105 and 107. Optical fibers 105 and 107 are further urged(as indicated by arrow 1501) toward mold 1007. As heat is conducted frommold 1007 into ends 101 and 103 of optical fibers 105 and 107,respectively, portions of ends 101 and 103 melt.

As illustrated in FIG. 16, the melted portions of ends 101 and 103 flowtogether, conforming to the geometric configuration of forming surface1013 of mold 1007 and fusing optical fibers 105 and 107 together,forming optical fiber device 201. In a preferred embodiment, mold 1007is allowed to cool to below the melting point of optical fibers 105 and107. Then, as depicted in FIG. 17, insert 1003 is withdrawn from guide1005 and optical fiber device 201 is removed from insert 1003. It shouldbe noted that the scope of the present invention, however, encompasses amethod wherein insert 1003 is withdrawn from guide 1005 without firstcooling mold 1007.

It should be noted that the particular geometric configuration offorming surface 1013 of mold 1007 and the resulting geometricconfiguration of end 203 of optical fiber device 201 are merelyexemplary. Other configurations exist and such configurations areencompassed within the scope of the present invention.

FIG. 18 depicts a third illustrative embodiment of an apparatus 1801according to the present invention for forming an optical fiber device,such as optical fiber device 201 of FIG. 2, from a plurality of opticalfibers, such as optical fibers 105 and 107 of FIG. 1. Apparatus 1801corresponds to apparatus 301 of FIG. 3, except that apparatus 1801includes a cooling means 1803 operatively associated with mold 305.Cooling means 1803 may comprise any suitable means for cooling mold 305from a temperature above the melting temperature of the optical fibersbeing formed into the optical fiber device to a temperature below themelting temperature of the optical fibers. In various embodiments,cooling means 1803 may comprise a fan urging air at an ambienttemperature or below over mold 305, a refrigerant system for coolingmold 305, or the like. Moreover, the scope of the present inventionencompasses a method, corresponding to the method described above inrelation to FIGS. 6-9, further including the step of cooling mold 305with cooling means 1903.

FIG. 19 depicts a fourth illustrative embodiment of an apparatus 1901according to the present invention for forming an optical fiber device,such as optical fiber device 201 of FIG. 2, from a plurality of opticalfibers, such as optical fibers 105 and 107 of FIG. 1. Apparatus 1901corresponds to apparatus 1001 of FIG. 10, except that apparatus 1901includes a cooling means 1903, corresponding to cooling means 1803described above, operatively associated with mold 1007. Moreover, thescope of the present invention encompasses a method, corresponding tothe method described above in relation to FIGS. 15-17, further includingthe step of cooling mold 1007 with cooling means 1803.

It should be noted that, while the drawings and the correspondingdescription provided above disclose various embodiments of the presentinvention operable to fuse a plurality of optical fibers into an opticalfiber device having a desired end configuration, the scope of thepresent invention is not so limited. Rather, the apparatus and method ofthe present invention may be used to thermally form a desired endconfiguration on a single optical fiber.

The particular embodiments disclosed above are illustrative only, as theinvention may be modified and practiced in different but equivalentmanners apparent to those skilled in the art having the benefit of theteachings herein. Furthermore, no limitations are intended to thedetails of construction or design herein shown, other than as describedin the claims below. Although the present invention is shown in alimited number of forms, it is not limited to just these forms, but isamenable to various changes and modifications.

1. An apparatus for forming an optical fiber device comprising at leastone optical fiber, the apparatus comprising: a mold including a formingsurface; means for heating the mold or the at least one optical fiber;and an insert defining at least one optical fiber locator passage forguiding at least one optical fiber toward the forming surface.
 2. Theapparatus according to claim 1, wherein the forming surface exhibits ageometric configuration inversely corresponding to a geometricconfiguration of an end of the optical fiber device.
 3. The apparatusaccording to claim 1, wherein the means for heating the mold comprisesan electromagnetic heating source.
 4. The apparatus according to claim1, wherein the means for heating the at least one optical fiber is anelectrical current discharge.
 5. The apparatus according to claim 1,wherein at least one of the mold and the insert comprises a materialexhibiting a melting temperature greater than a melting temperature ofthe at least one optical fiber.
 6. The apparatus according to claim 5,wherein the material comprises one of titanium and an alloy in which thealloy's principal element is titanium.
 7. The apparatus according toclaim 1, wherein the insert is removably mated with the mold.
 8. Theapparatus according to claim 7, wherein the insert defines an opticalfiber locator passage configured to accept a plurality of opticalfibers.
 9. The apparatus according to claim 8, wherein the optical fiberlocator passage is configured to accept a plurality of side-by-sideoptical fibers.
 10. The apparatus according to claim 7, wherein theinsert defines an oblong optical fiber locator passage in cross-section.11. The apparatus according to claim 7, wherein the insert defines aplurality of optical fiber locator passages configured to receive acorresponding plurality of optical fibers.
 12. The apparatus accordingto claim 1, further comprising means for cooling the mold.
 13. Theapparatus according to claim 1, wherein the forming surface of the molddefines a right-angle recess for forming the optical fiber device. 14.The apparatus according to claim 1, wherein the mold is constructed of acombination of two or more parts.
 15. The apparatus according to claim1, further comprising a guide affixed to the mold, the guide defining arecess configured to receive the insert and an optical fiber locatorpassage leading from the at least one optical fiber locator passage ofthe insert toward the forming surface.
 16. The apparatus according toclaim 15, wherein at least one of the mold, the insert, and the guidecomprises a material exhibiting a melting temperature greater than amelting temperature of the at least one optical fiber.
 17. The apparatusaccording to claim 16, wherein the material comprises one of titaniumand an alloy in which the alloy's principal element is titanium.